A wide variety of logging tools are often used to evaluate parameters of that a wellbore being drilled, the formation surrounding that wellbore, and/or the fluids within the wellbore. Where such logging tools rely upon acoustical measurements, there is often a need to isolate the sensors of acoustical signals from other components within the logging system. One clear example of such tools are acoustic logging tools which generate acoustic signals through a transmitter at one location on the tool (or in the tool string) and which travel through the formation to a receiver at a spaced location on the tool. Depending on the tool, the receiver may be spaced a few feet from the transmitter, or may be spaced 20 feet or more from the transmitter.
When such a system is operated, different types of waves propagate within the well and/or formation, including pressure waves (P-waves), shear waves (S waves), Rayleigh waves, mud waves and Stoneley waves. Of these wave types, P-waves and S-waves in particular, if unimpeded, can propagate along the body of the acoustic logging tool in a manner that would mask or otherwise adversely affect measurements by the acoustic receiver. Accordingly, there is a need to attenuate and/or slow down such propagation along the logging tool body so as to not adversely affect the measurements being made at the receiver. Additionally, the external contours of an acoustic isolator can couple acoustic energy between the logging tool and the formation surrounding the borehole, reducing the fidelity of the acoustic measurements. Accordingly, for some applications, an acoustic isolator having an external profile which approximates continuous and symmetrical surfaces would be advantageous.